BIRDS OF NORTH AND MIDDLE AMERICA. 693 



usually alike or nearly so and young not naaterially different from 

 adults, except sometimes in JRegulus and Polioptilinaa. 



Range. — Northern Hemisphere in general and greater part of Neo- 

 tropical Region, but most numerously represented in the Paleearctic 

 Region. (Numerous genera and species.) " 



The above diagnosis is based on the forms included under the 

 Sylviidee by Mr. Seebohm,** together with the genera Regulus and 

 PoUoptila, which I am unable to separate satisfactorily. Certainly 

 there is less structural difference between Regulus and Reguloides on 

 the one hand than between the latter and Sylvia on the other, Acan- 

 tJiopneiiste and other intermediate genera leading directly from Regvlus 

 toward Sylvia; consequently I can see no reason for separating Reg- 

 ulus from the Sylviidse, much less for referring it to the Paridse, as 

 has been done by some authors.* 



As to the exclusively American genus Polioptila, I am still in 

 doubt whether it snould be placed, among the Sylviidse. Its refer- 

 ence to the family Muscicapidse has been suggested by two authors,"^ 

 to the Mimidse by another;** the latter disposal of it I at one time 

 favored, but after carefully reconsidering the question I am con- 

 vinced that there is no group to which it can properly be referred 

 unless to the Sylviidse, the only alternative being the recognition of a 

 separate family (Polioptilidae). 



The only American groups with which any member of the Sylviidee 

 (as here defined) are likely to be confounded are the Paridse, Turdidse, 

 Mniotiltidse, and Vireonidse. From the first the Sylviidse differ in 

 more slender and notched bill, sharply ridged culmen, longitudinal 

 and operculate (usually exposed) nostrils," distinct rictal bristles, less 

 coherent toes, etc. ; from the second by the unspotted plumage of the 

 young; from the third by the obvious (though sometimes minute) 

 tenth primary, this being rudimentary and concealed in Mniotiltidse; 

 and from the fourth by the different structure of the toes, while the 

 species of SylViid^ which most resemble certain Vireonid* moreover 

 have the acrotarsium booted. 



Of the so-called subfamilies defined below, the Phylloscopinse are 

 so nearly peculiar to the Old World that only a single species, of 

 northeastern Asia, occurs in western Alaska, no other portion of the 

 American continent having a representative of the group. The sub- 



aCat. Birds Brit. Mus., v, 1881, 1-145. 



6 For example, Gadow, in Cat. Birds Brit. Mus., viii, 1883, 79-86, Seebohm, Hist. 

 Brit. Birds, i, 1883, 451, 452, and Hellmayr, Tierreich, 18, Lief., 1903, 7-15. 



cSharpe, Cat. Birds, Brit. Mus., x, 1885, 440, and Sclater, Argentine Ornithology, 

 i, 1888, 12. 



<*Stejneger, Standard Nat. Hist., iv, 1885, 504. 



«If the nostrils are hidden by feathers in Sylviidse the tarsi are booted (e. g. 

 -Regulus). 



